The present invention relates to electronic musical instruments and more particularly to an improved data encoder for use with an electronic organ, the data encoder having embodiments operable as a fill-note generator, a chord function generator and a "chimes" generator.
A keyboard instrument such as an electronic organ typically includes an upper or solo keyboard manual, a lower or accompaniment keyboard manual, a tone generator, a plurality of keyers coupling the tone generator to voice formant means which, in turn, are connected through an amplifier to a speaker. The keyers are operable in response to depressed keys on the keyboard manuals for supplying appropriate tone signals from the tone generator to the voice formant means and amplifier for sounding through the speaker. In addition, modern day electronic organs frequently utilize a time multiplexing mode of operation wherein the keys of one or both manuals are continuously scanned for developing encoded, time multiplexed serial data streams identifying the depressed keys of the respective keyboards. A demultiplexer subsequently decodes the data streams for enabling actuation of the appropriate keyers.
Various specialized circuits have been developed in the past for increasing the flexibility of and the ease with which such an organ may be played. Two such specialized circuits, the fill-note generator and the chord function generator, have gained particular popularity recently. Another such specialized circuit is commonly known as a "chimes" generator. All of these circuits have one basic feature in common; namely, augmenting or additional tone signals are generated internally by the organ in response to the depression of a key for creating a desired musical effect. Thus, a series of tone signals are processed by the organ even though only a single key is operated.
Prior art fill-note generators typically comprise means for automatically producing fill-in notes harmonizing with a melody note played on the upper keyboard manual, the fill-in notes being determined in accordance with a chord simultaneously played on the lower keyboard manual. Early implementations of such harmony generators were largely mechanical in nature requiring the provision of multiple switches simultaneously operative to close multiple conductive circuits and sometimes to open others, in response to depression of various keys of the keyboards. See, for example, U.S. Pat. No. 3,247,310 to H. B. Stinson, Jr.
Harmony of fill-note generators of electronic design were subsequently developed to overcome many of the deficiencies characterizing the prior art mechanical systems. The system disclosed in U.S. Pat. No. 3,745,225 to Hall is exemplary of such electronic designs. Even more recently, systems wholly digital in nature have been provided to perform the fill-note generating function. Exemplary of such systems are those disclosed in U.S. Pat. Nos. 3,939,051 to Moore and Pat. No. 4,112,802 to Robinson, et al. These digital systems generally operate on a time division multiplexed basis wherein a melody note played on the upper keyboard manual is represented by a single time displaced pulse and the fill-in harmonizing notes are represented by additional pulses coupled through the upper manual data channel and determined in conformity with a chord played on the lower keyboard manual.
Regardless of the type of system involved, i.e. whether mechanical, electronic or digital, various so-called "rules" dictated by musical considerations and preferences have evolved over the years governing the relationship between a melody note and the notes which may be utilized as fill-in notes for harmonizing therewith. Thus, in the case of closed harmony, the fill-in notes should be within the octave immediately below the melody note but not within two semitones thereof. In addition, there should be no octave doubling which would occur when a harmony note is generated exactly one octave below the melody note. The prior art systems all include means of one sort or another for operating in conformity with these "rules". In contradistinction to closed harmony, open harmony requires the sounding of fill-in notes in more than one octave below the melody note, with the closest fill-in note being no closer than five semitones from the melody note.
A "chimes" generator can be thought of as a very specific form of fill-note generator, the major difference being that the generated fill-in notes have a well defined relationship to the played melody note and are not determined in accordance with data supplied from the lower manual keyboard. As such, in response to the playing of an upper manual key, certain additional notes having a predetermined musical relationship to the melody note are automatically developed by the chimes generator and inserted in the upper manual data channel for enabling the production of a "chimes"-like tone.
Prior art fill-note generating systems are typically lacking in means for conveniently altering the relationship between a melody note and those notes from the lower manual keyboard selected for sounding through the upper manual data channel as harmonizing fill-in notes. Typically, only one such relationship is provided for, this relationship being alterable only by restructing the associated circuitry or, sometimes, by reprogramming certain memory circuits. Yet another problem characterizing prior art fill-note generating systems is the "muddying" effect produced when two or more rather closely spaced melody notes are played simultaneously. The foregoing results from the generation of too many fill-in notes and produces a close harmony or clashing effect which is highly unharmonious.
Chord function generators are also generally well known in the art and typically comprise means for automatically sounding a chord in response to the operation of a single key on the lower manual. Various circuits have been developed to perform this function, some exemplary embodiments of which are disclosed in U.S. Pat. Nos. 4,108,037 to Robinson et al., 4,065,993 to Hirose and 3,715,442 to Freeman. Yet another chord function generator is illustrated in U.S. Pat. No. 4,148,241.
In an effort to reduce the ultimate cost of an electronic organ, it is obviously desirable to provide circuits capable of being operated in more than one mode so that a number of features can be provided without significantly increasing the hardware costs associated with the instrument. Accordingly, it would be desirable to provide a data encoder which is capable of operation in a variety of modes so as to add to the versatility of the organ without significantly increasing its cost. In particular, it would be desirable to provide a data encoder having operational modes for producing the effects of a fill-note generator, a chord function generator and a "chimes" generator.